The present invention relates to an insulator element for lining at least one armature slot of an electrical machine. The present invention furthermore relates to a method for inserting winding elements into the slots of an armature and to an apparatus for performing the method.
It is known to line the slots of the armature of an electrical machine with the thinnest possible strips of paper. Lining the slots in this way serves to avoid damage to the winding elements, which for instance are in the form of painted copper wires, both in assembly and in offsetting at the sharp stamped edges of the lamination packets. The paper insulation used also offers a clamping action on the winding elements in the axial direction, so that the armature can be turned upon assembly. However, a paper insulation in the armature slot of this kind does not offer a radial hold for the winding elements. The radial change in location of the winding elements that is thus possible can adversely affect the initial imbalance of the armature. In addition to the introduction of the paper insulation, still another operation, known as xe2x80x9cwideningxe2x80x9d, is necessary to make it possible to introduce the winding elements, for instance in the form of copper wires, into the slots. As a further work step, the armature is often also impregnated with epoxy resin by means of immersion rolling. This positionally fixes the winding elements together with the paper in the armature slot. Also by means of this work step, a thermal binding to the armature packet can be attained. A disadvantage of this known procedure is that introducing the paper strips and the subsequent work steps are complicated, which is why especially in automated procedures, long cycle times are unavoidable.
Because the insulator element of the invention has at least one plastic element that is intended for lining an armature slot, the lining process can be performed quickly, which makes short cycle times possible in an automated procedure.
Preferably, each plastic element provided for lining an armature slot is tubular. The length of the tubular plastic elements is preferably adapted to the length of the armature slots. Because of the tubular shape of the plastic elements, it is possible to adapt both to the shape of the armature slot and to the geometry of the winding elements, which are in the form of copper conductors, for instance. Thus the winding elements can be disposed in a defined way, which has a favorable effect on the initial imbalance of the armature.
It is also preferably provided that the plastic element has a rib on its outside. This rib makes it possible for the further portions of the plastic element to be made with extremely thin walls, since the rib lends adequate strength.
The rib can be provided in order to close the armature slot when the plastic element is introduced into the armature slot. This closure of the armature slot has a favorable effect on armature noise, for instance.
The internal cross section of the plastic element can be substantially in the form of a figure-8. Preferably, the upper and lower portions of the 8 are joined to one another.
Preferably, the plastic element has at least one longitudinal furrow on its inside. By this at least one longitudinal furrow, an axial fixation in the plastic element is made possible, both on the inner side and on the outer side. Moreover, the at least one longitudinal furrow assures not only a compensation for tolerances between the slot and the winding elements but also that the potting composition used in an ensuing impregnation bathes the conductors on both the inside and outside. As a result, an optimal connection of the individual components (armature packet, insulator element and winding elements) can be assured.
Especially with a view to automated assembly, it can be advantageous that a plurality of plastic elements are connected to one another by at least one first connecting element in such a way that their mutual location corresponds to the mutual location of a plurality of armature slots.
To enable problem-free introduction of the winding elements into the plastic elements, the first connecting element can have one or more winding guide faces.
In an especially preferred embodiment, the first connecting element is annular. On an annular connecting element, a number of plastic elements corresponding to the number of armature slots can be disposed, so that in automated assembly, all the armature slots can be simultaneously lined with plastic elements.
Particularly for this purpose, it is advantageous if the first connecting element connects first adjacent end portions of plastic elements that are disposed essentially parallel.
In this connection, it can be provided that the first annular connecting element connects the end faces of a plurality of plastic elements, and that the first annular element has openings, which are adapted essentially to the cross section of the plastic elements. The aforementioned winding guide faces can in this respect be provided especially advantageously in the region of the openings. Moreover, an accumulation of material on one side of the annular connecting element can be achieved, which makes it easier to extrude the thin-walled plastic elements.
Moreover, a second connecting element can be provided. By means of this second connecting element, the plastic elements can be fixed in their mutual location over their full length.
The second connecting element is also preferably annular, especially if the first connecting element is annular.
This annular second connecting element can then connect the other adjacent end portions of the plastic elements that are disposed essentially parallel.
To that end, the annular second connecting element surrounds the plastic elements, preferably in such a way that the outside of the plastic elements rests on the inside of the annular second connecting element or is joined to it.
Especially in this case, it is advantageous that the second connecting element is connected to the plastic elements via rated breaking points. If desired, after the plastic elements have been introduced into the armature slots, the second connecting element can be sheared off manually or by an assembly tool. An ensuing metal-cutting operation for removing the connecting element is also conceivable, such as turning the outer diameter of the armature on a lathe. By the cooperation of the first connecting element and the second connecting element with the plastic elements, the insulator elements thus formed are protected against damage, for instance during shipping. Moreover, such insulator elements can be stored and/or shipped as bulk goods, since the individual insulator elements can be effectively prevented from catching on one another. In contrast to the conventional paper inlays, the insulator elements of the invention can thus be delivered with conventional xe2x80x9cpick and placexe2x80x9d equipment without major effort.
The second connecting element can also have at least one guide face, which is intended to facilitate the mounting of the insulator element on the armature. In this connection, it is for instance conceivable for an annular second connecting element that is disposed on the other end portions of the plastic elements to be widened radially toward the end of the insulator element. In that case, the annular second connecting element upon introduction of the plastic elements into the armature slots slides over the armature surface that is interrupted by the armature slots.
Because the method of the invention for inserting winding elements into the slots of an armature includes the following steps:
a) introducing an insulator element of one of claims 1-17 into at least one armature slot; and
b) inserting armature winding elements into the at least one plastic element,
it is possible, for instance in an automated procedure, to shorten the cycle times markedly. This offers a simple way of meeting the demands made in terms of the slot insulation, mechanical strength upon offsetting of the conductors, automated introduction of the winding elements, for instance in the form of copper wires, and the prefixation of the winding elements in the axial and radial directions.
In the method of the invention, the following further step is preferably provided:
c) filling interstices between plastic elements and armature slots and/or plastic elements and winding elements with potting composition.
This potting composition can for instance be formed by a resin, which assures an optimal joining of the individual components.
The method of the invention furthermore preferably provides that at least one connecting element is removed after the introduction of the insulator element into the slots. The connecting element to be removed can for instance be formed by the annular second connecting element, which is joined to the plastic elements by the rated breaking points. In that case, the annular second connecting element can simply be sheared off. Especially if rated breaking points are absent, however, a metal-cutting method is also conceivable for removing a connecting element.
Apparatuses that are suitable for performing the method of the invention are also covered by the patent scope of the associated claims.